Derivatization of carbon surfaces, i.e. the covalent attachment of molecules to the surface of elemental carbon, has attracted considerable interest in recent years, in particular in connection with attaching molecules to carbon nanotubes.
The derivatization of carbon may be carried out for a range of purposes which include modification of the surface properties of a carbon substrate, preparation of carbon-epoxy composites and attaching a molecule to a carbon electrode so that it can take part in an electrochemical reaction in an electrochemical sensor or an electrochemical catalyst.
Traditionally, carbon surfaces were modified by vigorous oxidation on the surface leading to the formation of carboxylic, quinonic, ketonic or hydroxylic groups, which were then reacted further with the target molecule. This aggressive process was difficult to control.
A number of procedures have been described for electrochemical induced derivatization leading to the formation of a single covalent bond between a carbon electrode and a moiety which becomes attached.
There have also been a number of disclosures of routes for derivatization of carbon, without electrochemistry. These include the homogeneous reduction of diazonium compounds in reducing media—see Pandurangappa et al Analyst, vol 127, page 1568 (2002) and Leventis et al, Talanta vol 63, page 1039 (2004). Also in this category is WO2005/066618 (Schlumberger) which describes the diazocoupling of anthraquinonyl and nitrophenyl groups onto carbon nanotubes by means of the reduction of diazonium salts. WO2010/106404 teaches exposing the carbon to a reaction mixture in which a reactive carbene is transiently formed by reaction between a precursor and an extremely strong base.